Vertical lift door safety latch



Oct. 4, 1966 w. H. PURCELL VERTICAL LIFT DOOR SAFETY LATCH Filed Oct. 19, 1964 FIG-1.1

INVENTOR.

WILLIAM H. PURCELL I 4 j ziw AT TORNEYS a-nd door supporting cables.

Filed Oct. 19, 1964, Ser. No. 404,805 Claims. (Cl. 49 322 The invention relates to vertical lift doors and refers more specifically to a safety latch for a vertical lift door constructed and arranged to be activated by the weight of the door in response to breaking of a door supporting The rapid closing of a vertical lift door due to gravity on breaking of a supporting cable therefor is dangerous to personnel and may result in substantial damage to property beneath the door as well as to the door. It is there-fore desirable to equip a vertical lift door with a safety latch to prevent rapid closing thereof on breaking of a door supporting cable.

In the past, where a safety latch has been provided on a vertical lift door, it has usually been actuated by a spring or other mechanism substantially independent of the door Prior safety latches have therefore been subject to failure at the time of the emergency for which a safety latch is provided since they have normally then been in an inactivated position for a considerable length of time and may have been corroded or painted over'in their open position or otherwise rendered inoperative under the forces usually provided for activation thereof.

It is therefore an object of the present invention to provide an improved safety latch for vertical lift door structure.

An other object is to provide a safety latch for vertical lift door structure constructed and arranged to be activated failure of the other door supporting cable.

Another object is to provide a safety latch as set forth "above including spring actuating means operable to close the latch on simultaneous failure of both door supporting cables.

Another object is to provide a safety latch for vertical lift doors which is simple in construction, economical to manufacture and efficient in use.

Other objects and features of the invention will become apparent as the description proceeds, especially when taken in conjunction with the accompanying drawing, ilnlustrating a preferred embodiment of the invention, where- .in'

FIGURE 1 is a diagrammatic representation of a vertical lift door, door operating mechanism and safety latch structure constructed in accordance with the invention.

FIGURE 2 is an enlarged elevation view of the safety latch structure at one side of the vertical lift door illustrated in FIGURE 1 shown in relation to a portion of the door frame with which it is operatively associated.

FIGURE 3 is a transverse cross section of the safety .latch structure and door frame portion illustrated in FIGURE 2 taken substantially on the line 3--3 in FIG- URE 2.

With particular reference to the figures of the drawing, one embodiment of the present invention will now be considered in detail.

The vertical lift door structure 10, illustrated best in FIGURE 1, includes the door 12, the 'door operating mechanism 14 and the safety latch structures 16 at the opposite sides of the door 12. The safety latch struc- United States Patent() "ice tures 16 include the latch member 18 cooperable with a toothed member 20 of the door frame 22 to prevent rapid descent of the door 12.

In operation the door supporting cables 24 and 26 of the door operating mechanism 14 hold the latch member 18 of the safety latch structures 16 in the unlatched position illustrated in FIGURE 2. Should one of the door supporting cables 24 or 26 break the other door supporting cable will apply the weight of the door 12 to the associated safety latch structures 16 to pivot the latch member 18 thereof into engagement with the cooperating toothed door frame member 20 to prevent descent of the door 12. In the unlikely event both door supporting cables 24 and 26 fail simultaneously, a spring 28 is provided to actuate each safety latch structure 16 to prevent rapid descent of the door 12.

More specifically the door 12 includes the door panel 30 for enclosing the space between the panel frame 32. Panel frame 32, as shown, may be channel members opening inwardly and defining the generally rectangular outline of the door panel 30. As shown best in FIGURE 3, a second outwardly opening channel member 34 is provided at the edges of door 12 secured to the inwardly opening channel members of panel frame 32 by convenient means, such as welding.

The inwardly opening channel members of panel frame 32 provide support for the door panel 30 and support for the safety latch structures 16 at the sides of the door 12. The outwardly opening channels 34 are guides to guide the door 12 in vertical movement within the door frame 22 of the door structure 10.

The door frame '22 of the door structure 10 includes the vertically extending member 38 terminating at one side in the rectangular structure 40 which may be conveniently set into an opening in a building or the like (not shown) and secured to the building. Separate angle members 42 and 44 are secured to the door frame member 38 at the front of the door 12 by convenient means, such as welding. The toothed angle frame members 20 cooperate with the angle members 42 and 44 and frame member 38 to provide a recess at each side of door 12 in which the door is moved. As pointed out above the angle members 20 are provided with a toothed outer edge 3-6 previously referred to which is cooperable with the latch members 18 of the safety latch structures 16 to prevent r-apid descent of the door 12 of door structure 10 should a supporting cable 24 or 26 of the door operating mechanism 14 break.

The door operating mechanism 14, as best shown in FIGURE 1, includes a cable drum 48 on which the door supporting cables 24 and 26 may be WOllIld or unwound on driving the cable drum 48 in opposite directions. The cable drum 48 may be connected for rotation in opposite directions to a reversible motor (not shown).

The door operating mechanism 14 further includes the cables 24 and 26. 'The cable 24 is passed over the fixedly positioned rotatable pulley 50 and then under the pulley 52 rotatably secured to the safety latch structure 16 at the right hand side of door '12 in FIGURE 1. Cable 24 then extends across the door 12 and is fixed to the pulley 54 rotatably connected to the safety latch structure 16 at the left hand side of the door in FIGURE l. The door supporting cable 26 is passed over the fixedly positioned rotatable pulley 56, under the rotatably mounted pulley 58, across the door 12 and is then fixed to the rotatably mounted pulley 60 of the door latch structure 16 at the right hand side of door 12.

Thus, in operation, as the cable drum 48 is rotated in a clockwise direction, as shown in FIGURE 1, both of the cables 24 and 26 will be caused to shorten the same amount to raise the door 12 within the door frame 22. Conversely, as the cable drum 48 is rotated in the opposite direction, the door 12 will be allowed to descend under controlled conditions as the supporting cables 24 and 26 are unwound from the cable drum 48.

Each safety latch structure 16 includes a U-shaped mounting bracket 62 secured by convenient means, such as welding, to an inwardly opening channel member of door frame 32, as illustrated. The bracket 62 includes side portions 80 and 82 having openings 64 extending therethroug-h in which a spring mounting pin 66 is secured. Bracket 6-2 also includes the aligned openings 68 extending transversely therethrough in which the pivot pin 70 mounting the latch member 18 is secured.

A pulley mounting member 72 including the side members 74 and 76 and the connecting sleeve 78 is p-ivotally mounted on the pin 70 between the side portions 80 and 82 of the bracket 62. Pulleys 54 and 58 are mounted for rotation on the pivot pin 84 at one end of the pulley mounting member 72, while the spring mounting pin 86 is secured at the other end of the pulley mounting member 72. Shaft 70 extends through the connecting sleeve 78 of the pulley mounting member 72 and is secured thereto by pin 88. The pin 70 and the latch member 18 are rigidly secured together.

A spacing member 90 is secured to the side portion 82 of the mounting bracket 62 to space the latch member 18 from the mounting bracket 62. Also, secured to the mounting bracket 62 are the rectangular stops 92 and 94. Stop 92 extends outwardly from the side portion 82 of the mounting bracket 62 and engages the latch member 18 with the latch member 18 in the latched position shown in phantom in FIGURE 2. Stop 94 which is positioned between the side portions 88 and 82 of the mounting bracket 62 engages the pulley mounting member 72, as shown in FIGURE 2, with the latch member 18 in an open or unlatched position. Thus, the stops 92 and 94 provide the limits of movement for the latch member 18.

The spring 28 is mounted on the pins 66 and 86 as previously indicated and serves to urge the pulley mounting member 72 in a direction to place latch member 18 in a latched position. Thus should both door supporting cables 24 and 26 fail simultaneously, the springs 28 will actuate the safety latch structures 16.

In over-all operation of the vertical lift door structure 18, and particularly considering the safety l-atch structure 16 at the left of door 12 in FIGURE 1, the door supporting cable 26 which passes under the pulley 58 will provide a force resultant on the pulley in a direction making an angle of approximately forty-five degrees with respect to the horizontal and vertical direction of extension of the cable 26, as shown by arrow 168 in FIGURE 2. The cable 24 at the same time will provide a horizontal force acting on the pulley 54. The resultant of the forces acting on the pulleys 54 and 58 is a force acting at substantially twenty-two and one-half degrees with respect to the horizontal, as shown by arrow 182 in FIGURE 2. As shown best in FIGURE 2, the twenty-two and onehalf degree resultant force passes through the center of the axis of pin 7 with the latch 18 in an unlatched limited position.

Should the cable 26 break, the horizontal force applied to the pulley 50 due to the weight of the door 12 through cable 24 will rotate the latch member 18 into a latched position, as shown in dotted lines in FIGURE 2 wherein the end 96 of the latch 18 will engage the toothed edge 36 of the frame angle 28 to prevent rapid descent of the door 12 due to breaking of the cable 26.

In a similar manner, if the cable 24 should break, the safety latch structure 16 at the right of the door 12 would be actuated through cable 26 to hold the door 12 open. In the very unlikely situation where both cables 24 and 26 would break simultaneously, the springs 28 are provided to ctuate both of the safety latch structures 16.

It will be seen that the safety latch structure 16 is particularly desirable since with such structure the full weight of the door which may provide a force of for example one thousand pounds is used to actuate the structure when needed. Thus forces caused by corrosion, painting over and the like which may prevent prior safety latches from operating are overcome with the disclosed safety lat-ch structure.

While one embodiment of the present invention has been disclosed in detail other embodiments and modifications are contemplated. It is the intention to include all embodiments and modifications as are defined by the appended claims within the scope of the invention.

What I claim as my invention is:

1. Vertical lift door structure comprising a door, a frame for the door including a vertically extending toothed member at each side thereof, door actuating mechanism for controlled moving of the door in a vertical direction including a cable drum, a pair of door supporting cables secured to said drum for winding and unwinding on rotation thereof, a pair of fixed pulleys at opposite sides of the door over which separate ones of the cables extend, a pair of pulleys movable with the door at each side of the door under one of which the cable at the same side of the door is passed and to the other of which the cable at the opposite side of the door is secured after passing under the pulley at the opposite side of the door and safety latch structure positioned at each side of the door including a mounting bracket secured to the door, a latched member pivotally mounted on the mounting bracket for pivoting into a latched position wherein it engages the toothed member of the door frame to prevent downward movement of the door and into an unlatched position in which free movement of the door is permitted, a pulley mounting member mounted in the mounting bracket for pivotal movement with the latch and mounting said pulleys movable with the door at the opposite sides of the door for providing a force resultant through the pivot axis of the pulley mounting member and latch with the latch in an unlatched position and providing a force resultant to pivot the latch into a latched position on failure of the door supporting cable at the same side of the door.

2. Structure as set forth in claim 1 and further including a stop secured to the mounting bracket engageable with the latch to limit rotation of the latch in a latching direction.

3. Structure as set forth in claim 1 and further including a stop secured to the mounting bracket engageable with the pulley mounting member to limit rotation of the pulley mounting member in a direction to unlatch the latch.

4. Structure as set forth in claim 1 and further including spring means operable between the pulley mounting member and mounting bracket for urging the pulley mounting member in a direction to move the latch into a latched position to prevent uncontrolled closing of the door on simultaneous failure of both door supporting cables.

5. Safety latch structure for a door movable between upper and lower positions, having cables sustaining. the weight of the door held in tension and operating means connected to said cables for raising and lowering the door, said safety latch structure comprising a latch device mounted on the door and movable between latching and unlatching positions, cooperating means adapted to be engaged by said latch device in the latching position of the latter to prevent the descent of the door, one of said cables engaging said latch device and imposing a force thereon through the tension in said one cable so as to urge said latch device to its latching position, the other cable engaging said latch device and imposing a force thereon through the tension in said other cable so as to hold said latch device in unlatching position against the action of the first cable but in the event of failure of said other cable permitting said latch device to be moved to said latching position by the action of said one cable.

6. Safety latch structure for a door movable between upper and lower positions having first and second cables which sustain the weight of the door and are thereby maintained in tension and operating means connected to said cables for raising and lowering the door, said safety latch structure comprising latch devices movable between latching and unlatching positions, cooperating means adapted to be engaged by said respective latch devices in the latching positions of the latter to prevent the descent of the door, said first cable having a first engagement with one of said latch devices and a second engagement with the other of said latch devices, said second cable having a first engagement with said other latch device and a second engagement with said one latch device, said cables through their second engagements with said latch devices urging the latter to their latching positions, and through their first engagements with said latch devices holding the latter in their unlatched positions against the force of the first engagement, the failure of either cable relieving the associated latch device from the force of the first engagement therewith to permit the latter to be moved to its latching position under the force of the second engagement therewith.

7. The safety latch structure defined in claim 6, wherein said latch devices are located adjacent opposite edges of said door and the cooperating means engageable with said respective latch devices are located adjacent opposite edges of said door.

8. The safety latch structure defined in claim 7, wherein said first cable extends downwardly to said one device and an intermediate portion thereof provides said first engagement with said one device, and then extends across to said other device to which it is terminally connected to provide said second engagement with said other device, said second cable extending downwardly to said other device and having an intermediate portion thereof providing said first engagement with said other device, and then extending across to said one device to which it is terminally connected to provide said second engagement with said one device.

9. The latch structure defined in claim 8, said latches being pivotally connected to said door, said cables being terminally connected to said latch devices as aforesaid at points spaced from the pivot axes of said latch devices, said intermediate portions of said cables having said first engagements with said latch devices at points spaced from the pivot axes of said latch devices.

10. The structure defined in claim 9, wherein said latch devices have pulleys around which the intermediate portions of said cables extend to provide said first engagements.

References Cited by the Examiner UNITED STATES PATENTS 1,404,053 1/ 1922 Peelle 26874 HARRISON R. MOSEIJEY, Primary Examiner.

J. K. BELL, Assistant Examiner. 

5. SAFETY LATCH STRUCTURE FOR A DOOR MOVABLE BETWEEN UPPER AND LOWER POSITIONS, HAVING CABLES SUSTAINING THE WEIGHT OF THE DOOR HELD IN TENSION AND OPERATING MEANS CONNECTED TO SAID CABLES FOR RAISING AND LOWERING THE DOOR, SAID SAFETY LATCH STRUCTURE COMPRISING A LATCH DEVICE MOUNTED ON THE DOOR AND MOVABLE BETWEEN LATCHING AND UNLATCHING POSITIONS, COOPERATING MEANS ADAPTED TO BE ENGAGED BY SAID LATCH DEVICE IN THE LATCHING POSITION OF THE LATTER TO PREVENT THE DESCENT OF THE DOOR, ONE OF SAID CABLES ENGAGING SAID LATCH DEVICE AND IMPOSING A FORCE THEREON THROUGH THE TENSION IN SAID ONE CABLE SO AS TO URGE SAID LATCH DEVICE TO ITS LATCHING POSITION, THE OTHER CABLE ENGAGING SAID LATCH DEVICE AND IMPOSING A FORCE THEREON THROUGH THE TENSION IN SAID OTHER CABLE SO AS TO HOLD SAID LATCH DEVICE IN UNLATCHING POSITION AGAINST THE ACTION OF THE FIRST CABLE BUT IN THE EVENT OF FAILURE OF SAID OTHER CABLE PERMITTING SAID LATCH DEVICE TO BE MOVED TO SAID LATCHING POSITION BY THE ACTION OF SAID ONE CABLE. 